It is known in the art of photography to use quaternary ammonium salt polymers, such as those described in, for example, U.S. Pat. Nos. 3,709,690, 3,958,995 and 3,898,088, as mordants for fixing anionic dyes. While polymers of this type function as good mordants for anionic dyes, they are deficient in keeping the mordant-fixed dyes in a stable condition. A photographic system containing a dye image mordanted with such a dye mordant has another disadvantage in that the mordanted image dye is liable to undergo chemical change or degradation upon exposure to fluorescent light, solar radiation or the like.
On the other hand, the polymers having a tertiary imidazole ring system in the side chain as described in, for example, British Patent No. 2,056,101, U.S. Pat. Nos. 4,115,124, 4,282,305, and 4,273,853, are capable of keeping the mordanted dyes stable against light but are deficient in mordanting activity.